[waves crashing] [water splashing] [bright music] [sea lion barking] [inspirational music] - It would be impossible to overestimate the impact of this one book.

Not only did the theory of evolution through natural selection revolutionized the natural sciences it changed forever the way man viewed his own position in the natural world.

Hi, I'm George Page for Nature.

And this week we returned to the Galapagos Islands where Charles Darwin made the observations which inspired the theories he put down in this book In 1859.

Although widely accepted by scientists, it is one of the most controversial books ever written.

And to this day there are those who consider it a work of the devil.

In it, Darwin says that man is just one remarkable species in a world of related and equally remarkable species.

That there is a kinship among all the living creatures on earth, including man.

Darwin's discovery was possible because the isolation of the Galapagos Islands highlights the play of the evolutionary forces.

They've been called a living showcase of evolution.

Hundreds of miles of oceans separate them from the nearest land mass, and although on the equator they're surrounded by cold, polar currents which isolate the islands, even from each other.

Our film this time is about those animals that live under and beside the violent Galapagos surf and nowhere else on earth.

And thanks to the latest techniques of underwater photography we will see things that Darwin never saw.

[inspirational music] [birds chirping] The Galapagos Islands lie 600 miles out in the Pacific off the coast of Ecuador.

[waves crashing] They have various unofficial names including Darwin's Islands and the Enchanted Isles, because the old time navigators had great difficulty in finding them.

[waves crashing] Perverse winds and currents took their ships off course.

But the seas around them and the wealth of marine creatures those seas support are as improbable and intriguing as the islands themselves.

[waves crashing] The booby's dive parts a silver curtain of small fish.

Even though the islands lie right on the equator there's very little coral here.

The water's too cold.

The seabed consists of jumbled volcanic lava.

The water, chilly by tropical standards, is rich in nutrients.

The currents that bring this food are complex and can't always be relied on to deliver.

When they flow normally, the waters are a seething mass of fish.

The conditions can vary, even from island to island.

[light music] Amberjacks, hunters of the in shore waters.

This strange looking creature is a bumpheaded parrotfish.

A shoal of golden eagle rays.

A sting ray.

And a giant manta ray.

Like the manta, the whale shark, the largest fish in the ocean is harmless.

A sweeper up of the plankton swarms.

This one is more than 35 feet long.

Nor is there any shortage of the more lethal species of sharks.

10 foot hammerheads are almost as common as the shoals of fish they play upon.

[light music] The fish are only part of the underwater scene.

Green turtles are endangered almost everywhere else in the world's oceans.

In the Galapagos, they abound.

This is the only place in the world you can find a penguin on the equator.

[penguin squawking] Most live south in the cold Antarctic seas.

The Galapagos penguin is the most northerly of the worlds 14 species.

Even so they only nest in one small part of the Acapellago, and then only when the water is cold enough for them to breed.

[lively music] This is the only place too, where you can meet a large lizard swimming beneath the surface of the sea, the Galapagos marine iguana.

Pacific bottle nose dolphins delight in riding on the pressure wave from the bow of any boat that passes.

[water splashing] [lively music] Dolphins are common enough but not a school of more than 30 sperm whales.

They've been hunted out of existence practically everywhere else.

Galapagos sea lions, like so many other Galapagos creatures they're a separate subspecies.

The wealth of marine life in the Galapagos depends on a coincidence of currents and geography.

Driven by southeast trade winds, the cold Peru current sweeps up the coast of South America causing rich up-wellings from the seabed.

Off Peru it's diverted toward the Galapagos where it joins the west flowing south equatorial current.

These currents not only produce rich feeding, they lower the water temperature by several crucial degrees.

[waves crashing] The shoreline, and inshore waters of this comparatively cold, often turbulence sea, harbor a wonderfully diverse menagerie.

[waves crashing] [birds chirping] It's impossible to venture far along the rough lava shores of the main island without encountering the intimidating but quite harmless reptile, the marine iguana.

[waves crashing] The only marine lizard in the world, it's thought to have descended along with the Galapagos land iguana from a common lizard ancestor that reached the islands from the mainland hundreds of thousands of years ago.

It has brilliantly adapted to life on the shoreline.

The blunt snout allows it to graze seaweed close to the rocks.

The powerful legs are ideal for climbing rough, steep surfaces.

There's somewhat demonic appearance led Darwin to refer to these lizards as imps of darkness.

The dragon like crest serves to intimidate rival iguanas.

[waves crashing] [sea lion barking] But there can only be one candidate for the starring roll in the pageant of the shoreline, the Galapagos sea lion.

The original sea lion colonist probably came from California or Mexico Sea of Cortez far to the north.

[water splashing] All sea lions are playful but the Galapagos subspecies is especially so.

like most other wildlife in the enchanted aisles they're incredibly tame, both on shore and beneath the surface.

[water splashing] [sea lion barking] The Galapagos fur seal came from the south, lured thousands of years ago by the cold Peru current.

In the early part of this century, they were almost hunted out of existence for their thick under fur.

Their recovery began in the 1930s.

Today there are between 30 and 40,000 of them in the islands.

[waves crashing] [lively music] In an underwater grotto on the shoreline of the island of Santiago.

The sea lions joined fur seals in playing with a strip of nylon rigging lost by a passing boat.

[lively music] And after swimming, a period of relaxation, often enjoyed afloat, using upraised flippers both as sales and rudders.

[water splashing] The sea lions and fur seals are native permanent residents of the islands.

The green turtles just visit the Galapagos to mate and lay their eggs.

The green turtle is an endangered species due to exploitation of both adults and their eggs on tropical beaches everywhere.

Galapagos waters are probably the only place in the seven seas where you can be sure of seeing a pair mating.

[soft music] Not all courtship is as serene as this.

[water splashing] During the mating season, the beach masters, the adult sea lion bull, continually battle for dominance of territories and females.

[water splashing] [sea lion barking] No single beach master keeps control of his territory for more than two weeks or so, the wear and tear is far too great.

So mastery of the beach is always changing and challenges continually being met.

The cows mean time, manage to appear unconcerned.

A month after the pups are born, the females are ready to mate again.

This mother, quite exceptionally, has produced twins.

She doesn't at all like the postnatal attention of the Galapagos mockingbirds attracted to the remains of the placental sack.

These are Espanola mockingbirds.

[birds chirping] [sea lion growling] [pup crying] [waves crashing] [sea lion barking] The beach master is challenged by the younger bull on the right, but with weight, age, and experience on his side, the beach master prevails.

Later on, when he is more exhausted, the younger bull will have a better chance of taking over his territory.

[sea lion barking] [water splashing] [sea lion barking] [water splashing] For the moment, peace return to the sea lion beach.

[sea lions barking] Where there are sea lions, there are always flies and the yellow warbler exploits the situation.

[sea lion barking] [waves crashing] A mother takes her newborn pup, still trailing it's placental sac, to the water for the first time.

[sea lion barking] She's very cautious and keeps it in a pool surrounded by rocks.

[sea lion barking] Sharks are always on the lookout for unguarded sea lion pups and will swim within a few feet of the shore to grab them.

[sea lion barking] Sharks in the Galapagos become extremely bold in pursuit of prey though there's no record of them attacking humans.

About 20 reef sharks have cornered a shoal of needle fish in a small inlet in the shoreline.

[water splashing] One needle fish leaps out of the sharks jaws only to find itself drowning in air.

It wriggles back to the water to take its chance there again.

[water splashing] [sea lion barking] A cold sea on the equator, a sea full of nutrients brought by cold currents and rich upwellings.

Of all the marine animals that profit from what these currents bring, the Galapagos sea lion is always most in evidence.

It's the prima donna of Galapagos waters or perhaps the prima ballerina would be a better description.

[bright music] [bubbles whooshing] [sea lion barking] The abundance of life dependent on these cold equatorial waters doesn't stop at the water's edge.

The rocky shores of the Galapagos are home to yet another cast of strange characters.

Practically the entire world population of one to 2000 Galapagos flightless cormorants lives here around the narrow Boulevard Channel between the islands of Isabella and Fernandina.

The straight provides the cold, shallow food, rich waters and sheltered landing places which the cormorant needs.

This strange bird was not discovered until 1896.

The cormorant has wings or rather the remnants of wings, but they're no longer used for flying.

It exchanged flying efficiency for underwater efficiency long ago, probably because there were no land predators to threaten it in the Galapagos.

Courtship usually begins in the water.

The female, the far smaller of the pair, at first dive to escape the male's attention.

[water splashing] A pair sometimes keeps up this ritual for over an hour.

As she comes to accept the male, both thirds begin to dip their heads in the gesture called, snake necking.

As he becomes less aggressive, they swim together and strong surf doesn't deter them in the slightest.

[waves crashing] Eventually one bird, usually the male, leads the way ashore to continue the circling dance close to a nesting site.

The pair often display together at three or four possible nesting places.

[bird cooing] Circling on shore sometimes leads to an even longer and more complicated aquatic dance routine.

[water splashing] This time the female makes no attempt to escape her suitor.

The dance now has all the signs of a well cemented union.

[water splashing] [bird cooing] Evidence of advanced courtship is that they now perform not only the snake neck but a throwback of the head and bow.

[birds cooing] Fortunately, even with such a tiny world population there's no sign that this unique species is in danger.

The courting couple waddles out of the water at the sort of easy landing place essential to a flightless bird.

[waves crashing] This is not a suitable cormorant beach.

[waves crashing] Powerful surf is of no concern to marine iguanas.

This one's pink breeding colors match the warm glow of the octopus nearby.

The iguanas are grazing between the tides.

They're no danger to the octopus, quietly expelling water from its siphon.

Eventually the octopus decides to move away and submerge.

[waves crashing] After his five week visit to the islands, in 1835, Charles Darwin wrote that he believed the iguanas ate seaweed on the ocean floor.

Later naturalists contested this, claiming the lizards food was limited to seaweed exposed by the tide.

In fact, the iguanas do both.

However, they are not as Darwin thought, restricted to only one sort of seaweed.

They eat several species.

Their teeth form a very efficient serrated rasp for gnawing weeds off the rock.

[waves crashing] Who Sally Lightfoot was, no one these days seems to know.

One theory is that she was a Jamaicans dancer who gave her name to these red shore crabs.

They fall easy victims to underwater predators, so avoid submerging whenever possible.

[water splashing] [water splashing] Like the marine iguanas, they abound on practically every island in the group.

That small black iguana is a young one, not yet ready to breed.

The Sally lightfoot's main enemies on the shoreline are the night herons and lava herons.

[waves crashing] This lava heron waited until it's spotted a soft crab that had just shed its shell.

As the tide flows and the rock pools fill, the marine iguanas start to feed underwater just as Darwin forecast.

[water splashing] Adult iguanas have been observed grazing as much as half a mile offshore.

The smaller ones stay closer to the tide line.

[water moving] They swim by driving themselves along with movements of body and flattened tail.

Legs play no part and are held close to the sides.

[water splashing] The powerful legs come into their own when hauling out on lava rocks and running surfs.

[waves crashing] Though they can drink sea water they must expel surplus salt.

They do so by ejecting a fine spray from the nostrils.

[air puffing] Though the lava heron will take crabs, it must prefer small fish like these young mullet.

[birds chirping] At low tide, pools and the lava rocks are filled with stranded schools of them.

[water trickling] [birds chirping] [water moving] [birds chirping] [water trickling] [bird chirping] On some islands there are sandy beaches between the stretches of black lava shoreline.

In the early part of the year, they appear to have been the scene of a miniature tank battle.

[waves crashing] [bird cawing] The tracks lead to and from the sea.

They're made by egg laying, green turtles.

[sand rustling] Most females lay their eggs at night but this one is still busy at sunrise.

[wings flapping] A Galapagos dove mistakes her for a rock.

[sand rustling] The Galapagos is one of the few breeding places in the world where the green turtle and her eggs are safe from man.

However, domestic pigs introduced by settlers and gone wild are a serious menace.

On some beaches they dig up almost every nest.

A lava lizard, another Galapagos species, excavates her own nest close to where the turtle has just laid.

It's a female in breeding colors.

She won't do any damage.

The turtles themselves do that by digging up each other's nest because suitable beaches are so much in demand.

[bird cawing] [waves crashing] At last, the exhausted female reaches the sea.

[waves crashing] On a sandy beach, which the turtles wisely don't patronize, the sea lion pup are already boisterous and playful.

[water splashing] When not chasing each other, they find a variety of play things.

[sea lion growling] That's a pencil spine sea urchin.

[sea lion growling] Anything that moves is fair game.

A favorite sea lion pastime, for young and old alike, is pulling the marine iguanas tail.

[water splashing] There seems to be nothing aggressive about it.

You seldom see an iguana with the tip of its tail chewed off, and sea lions have very sharp teeth.

[water splashing] The iguana escapes, apparently none the worse for wear.

Birds come in for a good deal of sea lion teasing too.

Even birds as big as a brown pelican.

[water splashing] [waves crashing] All this play probably has a function in speeding reactions and alertness.

Alertness is a quality a young sea lion badly needs in Galapagos waters.

When the beaches are crowded with young the sharks come in looking for an unguarded pup.

[water splashing] [waves crashing] This shark, swimming in only a few feet of water is quite big enough to seize a pup or take a bite out of an adult.

[waves crashing] [sea lion barking] A pair of young bulls decides things have gone far enough.

Now there are at least three sharks in the shallows.

[water splashing] [waves crashing] [sea lion barking] The bulls were taking a big chance when they challenged the sharks.

This adult cow's rear flippers were bitten off in a previous shark attack.

[waves crashing] About 12 weeks after the eggs were laid at the top of a sandy beach, the young green turtles are ready to hatch.

[light music] Usually the young go down to the sea undercover of darkness.

When a batch waits until well after sun up they expose themselves to all kinds of danger.

The sleeping sea lions are no threat but they might as well be a mountain range, blocking the hatchling turtles path to the sea.

[soft music] By the time the first young reached the tides edge the predators have spotted them.

A cricket bird in.

[dramatic music] But the next little turtle makes it.

[waves crashing] The mockingbirds are quick to exploit any opportunity.

To a newly hatched turtle, their long beaks are lethal.

[bird chirping] A Galapagos hawk is next.

[bird chirping] [waves crashing] A disastrous hatching, but a few do reach the breakers there to take their chance with shoals of predatory fish.

[waves crashing] Because the sea temperature is appreciably lower than anywhere else on the equator, the marine life of the Galapagos is unlike that of any other tropical island group.

But sea lions everywhere seem determined to make the most of their opportunities to celebrate life.

It's hard to imagine the more exhilarating tribute to life triumph in the Galapagos, than an afternoon of body surfing in the rollers off Espanol.

[bright music] [waves crashing] [waves crashing] [waves crashing] [waves crashing] [sea lion barking] [waves crashing] [bright music]